iPod USB cables are what connect the MP3 player to your computer, wall and other accessories.  The iPod cable that comes with the device is special to the unit itself; it can only be used with an iPod, as it has a special connection into it.  The USB end then gets plugged into a USB-based port, whether that be on a computer, charger or other accessory.  It is important to realize that the iPod Shuffle has a different type of USB cable than any other iPod or iTouch on the market; since the iPod Shuffle is charged and connected via its headphone port, the other end of the USB cable then plugs into where you need it.

The iPod USB cables always comes bundled with the purchase.  From there, you may have to buy a new one down the line if you damage it, lose it or just want a second one in the event you need it.  You can buy the Apple-branded one or a third party one, depending on your needs.  Some iPod USB cables double as AV cables or other cable combinations.  The iPod USB cable is necessary to use the iPod as it lets you connect it to the computer so you can use iTunes to update the MP3 player, charge it and manage your multimedia on it.

iPod USB cables can be bought wherever iPods are sold, but they can also be purchased online.  When searching for the right iPod USB cable, make sure you purchase the USB version and not a FireWire cable.  Some consumers get the two mixed up.  The FireWire cable offers a high-speed of data transfer but often only charges an older generation iPod and is not compatible with newer versions of the device.  iPod USB cables will last forever it properly taken care of, so if you take the time taking care of it from the start the only other USB cable you will have to buy is the one you want, not need.